The undisputed enfant terrible of sumo wrestling returned from a three-month suspension today vowing to change his ways and restore the ancient sport's reputation as it confronts the biggest crisis in its 2,000-year history.

Asashoryu, considered one of the greatest wrestlers of all time, was banned from two tournaments after being filmed playing in a charity football match in August, days after he pulled out of a sumo exhibition tour with a back injury.

"I would like to apologise from the bottom of my heart for the concern and trouble I have caused my fans," the Mongolian grand champion told a packed press conference in Tokyo after flying in from Ulan Bator. "All I want to do now is fight to the best of my ability, and I hope you'll support me."

He responded to the ban - the harshest punishment meted out to a reigning yokozuna, or grand champion - by holing up in his Tokyo apartment, reportedly surviving on a diet of ready-made sandwiches.

At the end of August the sumo authorities gave him permission to return to Mongolia after he was diagnosed with a stress disorder. He has spent the past three months recuperating at a hot spring resort and, in the absence of training partners, struggling to stay in shape.

But he said: "Being back in my hometown in Mongolia among family and friends was the best possible medicine. I didn't know what was happening. I couldn't control myself. I was alone in my room and couldn't face people.

"Being in my home country helped me regain focus and bring my emotions back under control. I thought about many things and realised I had to change the way I think.

"The punishment was a big shock to me but it was my fault. From now on I will do my best to live up to the responsibility of being a yokozuna."

Asashoryu's return to the ring cannot come too soon for Japan's national sport. Sumo's struggle to repair its reputation following allegations that a junior wrestler was beaten to death by his stablemates in June was evident in the rows of empty seats at the most recent tournament.

Despite his relatively light 150kg frame, Asashoryu has combined fearlessness with unrivalled technique to rise to the top of the sumo rankings. Since becoming a yokozuna in 2003, he has won 19 tournaments, including seven in a row. His career total of 21 titles makes him the fifth-best wrestler of all time.

But to conservative sumo fans, he embodies all that has gone wrong with the ancient sport and lacks the dignity and humility befitting a grand champion.

He once grabbed the topknot of an opponent in the ring - a definite no-no - and scuffled naked in the bath with another Mongolian wrestler. His capacity for alcohol is legendary and he is reportedly experiencing marital problems.

In sumo terms, though, his biggest fault may be his nationality. Traditionalists yearn for the emergence of a homegrown champion to rise to the top and end the dominance of Asashoryu and sumo's only other yokozuna, fellow Mongolian Hakuho.

They could be in for a long wait: the latest top rankings, released this week, list a record 21 foreign professional wrestlers.

Looking slightly heavier than usual, Asashoryu calmly fielded numerous questions about the ill-fated football match, in which he appeared wearing a figure-hugging Wayne Rooney shirt.

He said he had only agreed to take part following pressure from the Mongolian government and Japanese embassy.

"I played in the match despite my injuries, and I regret that," he said.

His antics have provided the most compelling domestic sports story of the year. Japanese media organisations block-booked seats on his flight to Tokyo and several TV stations set aside other news this evening to carry live coverage of his press conference.

Asashoryu's journey of redemption continues at the weekend, when he is due to take part in an exhibition event before preparing for the next major tournament in the New Year.